Abstract
Contemporary theories suggest that mental imagery evolved to enable prospective simulation of future events for planning and decision-making (Suddendorf and Corballis, 2007; Schacter et al., 2008). Imagery allows organisms to construct hypothetical scenarios, enabling them to test alternative courses of action before acting (Moulton and Kosslyn, 2009). But how did mental imagery emerge from an evolutionary perspective?
I propose that imagery's origins lie in interoceptive processing, the phylogenetically ancient system linking internal bodily states to valence, emotion, and motivational salience (Craig, 2009; Barrett, 2017). Interoception is the necessary foundation for any planning system (such as imagery) because planning requires knowing what to plan for; which bodily and emotional states to pursue or avoid. Motor imagery emerged first, by extending forward models offline while inheriting interoceptive integration from survival-relevant actions. However, as social complexity in particular increased, organisms needed to simulate scenarios involving others (e.g., rival alliances, dominance conflicts, mating competitors) and here interoceptive signals alone proved insufficient, since the same autonomic arousal pattern can demand entirely different behavioral responses depending on context. Visual imagery evolved to solve this discriminability problem by binding distinctive sensory features with interoceptive states, creating multimodal representations where affective significance is constitutive of the image itself rather than a subsequent response to neutral sensory content.
What This Study Is About
This researcher wanted to figure out *why* humans evolved the ability to see pictures in their heads. He proposes that our "mind’s eye" actually grew out of our ability to feel what is happening inside our own bodies, like a racing heart or a nervous stomach.
How They Studied It
This wasn't a lab experiment with a group of people. Instead, it is a theoretical paper. The researcher acted like a detective, gathering evidence from many different scientific fields—including evolution, brain science, and psychology—to build a new explanation for how mental imagery (the ability to picture things in your mind) began.
What They Found
The study suggests that mental imagery evolved in three "levels" like a video game:
1. Level 1: Body Sensing. Early animals developed interoception—the ability to sense internal body signals (like hunger or fear).
2. Level 2: Action Planning. Animals then started "rehearsing" movements in their heads before doing them.
3. Level 3: The Picture Show. Finally, humans added visual "pictures" to these body feelings.
The researcher argues we didn't develop mental images just for fun; we developed them because a "feeling" of fear isn't specific enough. We needed a visual "movie" in our heads to distinguish between complex situations, like a rival trying to take our food versus a friend who is just grumpy.
What This Might Mean
For people with aphantasia (the inability to visualize), this theory suggests that their brains might still be doing the "Level 1" and "Level 2" work perfectly fine. They can plan actions and feel emotions, but their brains don't "bind" those feelings to a visual image.
It’s important to remember that because this is a theory paper, it doesn’t "prove" this is how it happened. Instead, it provides a "map" for other scientists to follow. It suggests that aphantasia isn't a "missing" feature, but perhaps a different way the brain handles the connection between the body and the mind.
One Interesting Detail
The paper points out that people with certain heart conditions (where the brain has trouble reading body signals) often have less vivid mental imagery. This suggests your "mind's eye" is actually plugged directly into your heart!